JP2003-74683A, published by the Japan Patent Office in 2003, discloses neutral control that reduces hydraulic pressure supplied to an automatic transmission clutch to maintain the clutch in a state immediately prior to engagement when a vehicle is stopped in an engine idling state. Feedback control may be used to perform neutral control. In feedback control, a slip amount of a torque converter (which equals the engine rotation speed minus the turbine rotation speed) is controlled to reach a target slip amount.